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Sat, 25 Apr 2026 13:40:32 -0700 (PDT) From: Jiri Olsa X-Google-Original-From: Jiri Olsa Date: Sat, 25 Apr 2026 22:40:30 +0200 To: Song Liu Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , stable@vger.kernel.org, bpf@vger.kernel.org, Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song Subject: Re: [PATCH bpf 1/2] bpf: Do not release trampoline image in case off unregister error Message-ID: References: <20260424153905.354922-1-jolsa@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Fri, Apr 24, 2026 at 08:50:51AM -0700, Song Liu wrote: > On Fri, Apr 24, 2026 at 8:39 AM Jiri Olsa wrote: > > > > If unregister_fentry fails we still have trampoline image attached > > to a function, so releasing it could trigger crash. Releasing the > > trampoline image only when the unregister succeeds. > > > > Cc: stable@vger.kernel.org > > Fixes: e21aa341785c ("bpf: Fix fexit trampoline.") > > Signed-off-by: Jiri Olsa > > The fix looks good. > > Acked-by: Song Liu > > Can we add a test case that triggers this crash without the fix? I don't about valid scenario where unregister_fentry would fail now, that'd be bug that we'd need to fix. We have WARN_ON_ONCE on tampoline unlink fail. The fix is meant for when this happens let's go with un-released trampoline image rather than kernel crash. jirka